This mesh is only based on the river points which are calculated by the random terrain generator. A more sophisticated approach would be to actually check the terrain heights to make sure that the river has neither gaps inside the river bed nor overflows outside the river bed.
Moreover it probably makes a lot of sense to split the river into multiple meshes for long rivers so the engine doesn't have to deal with the entire river all the time even though only small parts are visible.

Don't confuse s3sprite (Stranded III sprite module/library) and sprite (variable containing an actual sprite instance) here!
The difference is that you now call methods directly on the instance instead of passing it in as first parameter. This may not seem like a huge change but it makes scripts cleaner, shorter and easier to read.

Unfortunately I already wrote a few Lua scripts for Stranded III so I had to change over 600 function calls for this API change...

Shell
In the last dev blog I showed a little video where I modeled a shell. I continued working on the shell and recorded a video of me drawing the skin. People who subscribed to Unreal Software's YouTube channel probably already saw it because I uploaded it some days ago: Click to watch on YouTube!

The shell model would actually be a good candidate for a bump map. I drew the shading on separate layers in Photoshop so I could easily create a bump map from it. It would probably only need some small adjustments. I didn't give that a try yet though.